Incidence and risk factors of posterior cage migration following decompression and instrumented fusion for degenerative lumbar disorders

Development of End-to-End Artificial Intelligence Models for Surgical Planning in Transforaminal Lumbar Interbody Fusion

Transforaminal lumbar interbody fusion (TLIF) is a commonly used technique for treating lumbar degenerative diseases. In this study, we developed a fully computer-supported pipeline to predict both the cage height and the degree of lumbar lordosis subtraction from the pelvic incidence (PI-LL) after TLIF surgery, utilizing preoperative X-ray images. The automated pipeline comprised two primary stages. First, the pretrained BiLuNet deep learning model was employed to extract essential features from X-ray images. Subsequently, five machine learning algorithms were trained using a five-fold cross-validation technique on a dataset of 311 patients to identify the optimal models to predict interbody cage height and postoperative PI-LL. LASSO regression and support vector regression demonstrated superior performance in predicting interbody cage height and postoperative PI-LL, respectively. For cage height prediction, the root mean square error (RMSE) was calculated as 1.01, and the model achieved the highest accuracy at a height of 12 mm, with exact prediction achieved in 54.43% (43/79) of cases. In most of the remaining cases, the prediction error of the model was within 1 mm. Additionally, the model demonstrated satisfactory performance in predicting PI-LL, with an RMSE of 5.19 and an accuracy of 0.81 for PI-LL stratification. In conclusion, our results indicate that machine learning models can reliably predict interbody cage height and postoperative PI-LL.

Postoperative cage migration and subsidence following TLIF surgery is not associated with bony fusion

Pseudarthrosis following transforaminal interbody fusion (TLIF) is not infrequent. Although cage migration and subsidence are commonly regarded as evidence of the absence of solid fusion, there is still no evidence of the influence of cage migration and subsidence on fusion. This study aimed to evaluate cage migration and subsidence using computed tomography (CT) DICOM data following lumbar interbody fusion. The effects of cage migration and subsidence on fusion and clinical outcomes were also assessed. A postoperative CT data set of 67 patients treated with monosegmental TLIF was analyzed in terms of cage position. To assess the effects of cage migration and subsidence on fusion, 12-month postoperative CT scans were used to assess fusion status. Clinical evaluation included the visual analog scale for pain and the Oswestry Disability Index. Postoperative cage migration occurred in 85.1% of all patients, and cage subsidence was observed in 58.2%. Radiological signs of pseudarthrosis was observed in 7.5% of the patients Neither cage migration nor subsidence affected the clinical or radiographic outcomes. No correlation was found between clinical and radiographic outcomes. The incidence of cage migration was considerable. However, as cage migration and subsidence were not associated with bony fusion, their clinical significance was considered limited.

Biplanar Expandable Cages for Transforaminal Lumbar Interbody Fusion Are Safe and Achieve Good 1-Year Clinical and Radiological Outcomes in an Asian Population

BACKGROUND

This study investigated 1-year clinical and radiological outcomes of biplanar expandable (BE) cages following transforaminal lumbar interbody fusion (TLIF) in an Asian population.

METHODS

A retrospective review was conducted of all consecutive patients who underwent TLIF with BE cages performed by 2 fellowship-trained spine surgeons from 2020 to 2021. Inclusion criteria included open or minimally invasive (MIS) TLIF, of up to 3 spinal segments, performed for treatment of degenerative disc disease, spondylolisthesis, or spinal stenosis. Patient-reported outcomes, including visual analog score (VAS) for back and lower limb pain, Oswestry Disability Index (ODI) and North American Spine Society neurogenic symptom score (NSS), and various radiographic parameters, were evaluated.

RESULTS

A total of 23 patients underwent TLIF with BE cages with a follow-up duration of 1.25 years. Of those patients, 7 (30%) underwent 1-level TLIF, 12 (52%) underwent 2-level TLIF, and 4 (18%) underwent 3-level TLIF, with a total of 43 spinal segments fused. Four patients (17%) underwent MIS TLIF while 19 patients (83%) underwent open TLIF. VAS for back pain scores improved by 4.8 ± 3.4 (P < 0.001) from 6.5 ± 2.6 to 1.7 ± 2.2; VAS for lower limb pain scores improved by 5.2 ± 3.8 (P < 0.001) from 5.7 ± 3.4 to 0.5 ± 1.6; ODI scores improved by 29.0 ± 18.1 (P < 0.001) from 49.4 ± 15.1 to 20.4 ± 14.2; and NSS scores improved by 36.8 ± 22.1 (P < 0.001) from 53.3 ± 21.1 to 16.5 ± 19.8. Significant improvements in radiological parameters included increase in anterior disc height, posterior disc height, foraminal height, segmental lordosis, and lumbar lordosis. There were no implant-related complications, cage subsidence, cage migration, or revision surgery at 1 year.

CONCLUSIONS

TLIF performed with BE cages led to significantly improved patient-reported outcomes and radiographic parameters at 1 year and is safe for use in Asians.

CLINICAL RELEVANCE

The results of this study support the effectiveness and safety of TLIF with biplanar expandable cages.

LEVEL OF EVIDENCE: 4

A retrospective study on application of a classification criterion based on relative intervertebral tension in spinal fusion surgery for lumbar degenerative diseases

Background

As an important part of spinal fusion procedure, the selection of fusion cage size is closely related to the curative effect of the surgery. It mainly depends on the clinical experience of surgeons, and there is still a lack of objective standards. The purpose of this study is to propose the concept of relative intervertebral tension (RIT) for the first time and its grading standards to improve the surgical procedures of lumbar interbody fusion.

Methods

This retrospective study was conducted from January 2018 to July 2019. A total of 83 eligible patients including 45 men and 38 women with lumbar degenerative disease underwent transforaminal lumbar interbody fusion (TLIF) were included in this study. A total of 151 fusion segments were divided into group A, group B and group C according to the grading standards of RIT. In addition, parameters of intervertebral space angle (ISA), intervertebral space height (ISH), intervertebral space foramen (IFH), fusion rates, cage-related complications and cage heights were also compared among the three groups.

Results

The ISA in group A was the smallest among three groups in contrast with group C with largest ISA at the final follow-up(P < 0.05). The group A presented the smallest ISH and IFH values(P < 0.05), compared with group B with the largest ISH and IFH values(P < 0.05). These two parameters in the group C were in-between. The fusion rates of group A, group B and group C were 100%, 96.3% and 98.8% at the final follow-up, respectively. No statistical difference in fusion rates and cage-related complications occurred among the three groups(P > 0.05), and a certain correlation between ISH and RIT was also observed.

Conclusions

The concept of RIT and the application of its clinical grading standards could simplify the surgical procedures of spinal fusion and reduce cage-related complications.

A meta-analysis of risk factors for cage migration after lumbar fusion surgery

Objective

Cage migration is a rare complication after lumbar fusion surgery, and it is also the cause of lumbar revision surgery. Previous studies have reported that many influencing factors can increase the incidence of cage migration. However, there still remains controversial. The current study was conducted to investigate the risk factors influencing incidence of cage migration.

Methods

A systematic database search of PubMed, Embase, Web of Science, Cochrane Library and Clinical Trials was performed for relevant articles published until July 2022. According to the inclusion and exclusion criteria, two evaluators independently conducted literature screening, data extraction and quality evaluation of the obtained literature. The Newcastle-Ottawa Scale (NOS) score was used for quality evaluation, and meta-analysis was performed by STATA 16.0 software.

Results

A total of 2126 relevant articles were initially identified, and 7 articles were finally included in this study for data extraction and meta-analysis. The results of meta-analysis showed that the bony endplate injury, pear-shaped disc, and screw loosening are significantly correlated with cage migration. The OR values (95%CI) of the three factors were 7.170 (3.015, 17.051), 8.056 (4.050, 16.023), and 12.840 (3.570, 46.177) respectively.

Conclusion

Bony endplate injury, pear-shaped disc, and screw loosening are the current risk factors for cage migration postoperatively.

Novel MRI-based vertebral bone quality score as a predictor of cage subsidence following transforaminal lumbar interbody fusion

OBJECTIVE

Decreased bone mineral density as measured by dual-energy x-ray absorptiometry (DEXA) has been reported to be associated with cage subsidence following transforaminal lumbar interbody fusion (TLIF). However, DEXA is not often available or routinely performed before surgery. A novel MRI-based vertebral bone quality (VBQ) score has been developed and reported to be correlated with DEXA T-scores. The authors investigated the ability of the VBQ score to predict cage subsidence and other risk factors associated with this complication.

METHODS

In this retrospective study, the authors reviewed the records of patients who had undergone single-level TLIF from March 2014 to October 2015 and had a follow-up of more than 2 years. Cage subsidence was measured as postoperative disc height loss and was graded according to the system proposed by Marchi et al. The MRI-based VBQ score was measured on T1-weighted images. Univariable analysis and multivariable binary logistic regression analysis were performed. Ad hoc analysis with receiver operating characteristic curve analysis was performed to assess the predictive ability of the significant continuous variables. Additional analyses were used to determine the correlations between the VBQ score and T-scores and between the significant continuous variables and the amount of cage subsidence.

RESULTS

Among 242 patients eligible for study inclusion, 111 (45.87%) had cage subsidence after the index operation. Multivariable logistic regression analyses demonstrated that an increased VBQ score (OR 14.615 ± 0.377, p < 0.001), decreased depth ratio (OR 0.011 ± 1.796, p = 0.013), and the use of kidney-shaped cages instead of bullet-shaped cages (OR 2.766 ± 0.358, p = 0.008) were associated with increased cage subsidence. The VBQ score was shown to significantly predict cage subsidence with an accuracy of 85.6%. The VBQ score was found to be moderately correlated with DEXA T-scores of the total hip (r = -0.540, p < 0.001) and the lumbar spine (r = -0.546, p < 0.001). The amount of cage subsidence was moderately correlated with the VBQ score (r = 0.512, p < 0.001).

CONCLUSIONS

Increased VBQ scores, posteriorly placed cages, and kidney-shaped cages were risk factors for cage subsidence. The VBQ score was shown to be a good predictor of cage subsidence, was moderately correlated with DEXA T-scores for the total hip and lumbar spine, and also had a moderate correlation with the amount of cage subsidence.

Revision for cage migration after transforaminal/posterior lumbar interbody fusion: how to perform revision surgery?

Background

Symptomatic pseudarthrosis and cage migration/protrusion are difficult complications of transforaminal or posterior lumbar interbody fusion (TLIF/PLIF). If the patient experiences severe radicular symptoms due to cage protrusion, removal of the migrated cage is necessary. However, this procedure is sometimes very challenging because epidural adhesions and fibrous union can be present between the cage and vertebrae. We describe a novel classification and technique utilizing a navigated osteotome and the oblique lumbar interbody fusion at L5/S1 (OLIF51) technique to address this problem.

Methods

This retrospective study investigated consecutive patients with degenerative lumbar diseases who underwent TLIF/PLIF. Symptomatic cage migration was evaluated by direct examination, radiography, and/or computed tomography (CT) at 1, 3, 6, 12, and 24 months of follow-up. Cage migration/protrusion was defined as symptomatic cage protrusion > 5 mm from the posterior border of the over and underlying vertebral body compared with initial CT. We evaluated patient characteristics including body mass index, smoking history, fusion level, and cage type. A total of 113 patients underwent PLIF/TLIF (PLIF n = 30, TLIF n = 83), with a mean age of 71.1 years (range, 28–87 years). Mean duration of follow-up was 25 months (range, 12–47 months).

Results

Cage migration was identified in 5 of 113 patients (4.4%). All cases of symptomatic cage migration involved the L5/S1 level and the TLIF procedure. Risk factors for cage protrusion were age (younger), sex (male), and level (L5/S1). The mean duration to onset of cage protrusion was 3.2 months (range, 2–6 months). We applied a new classification for cage protrusion: type 1, only low back pain without new radicular symptoms; type 2, low back pain with minor radicular symptoms; or type 3, cauda equina syndrome and/or severe radicular symptoms. According to our classification, one patient was in type 1, three patients were in type 2, and one patient was in type 3. For all cases of cage migration, revision surgery was performed using a navigated high-speed burr and osteotome, and the patient in group 1 underwent additional PLIF without removal of the protruding cage. Three revision surgeries (group 2) involved removal of the protruding cage and PLIF, and one revision surgery (group 3) involved anterior removal of the cage and OLIF51 fusion.

Conclusions

The navigated high-speed burr, navigated osteotome, and OLIF51 technique appear very useful for removing a cage with fibrous union from the disc in patients with pseudarthrosis. This new technique makes revision surgery after cage migration much safer, and more effective. This technique also reduces the need for fluoroscopy.

Influence of the geometric and material properties of lumbar endplate on lumbar interbody fusion failure: a systematic review

Background

Lumbar interbody fusion (LIF) is an established surgical intervention for patients with leg and back pain secondary to disc herniation or degeneration. Interbody fusion involves removal of the herniated or degenerated disc and insertion of interbody devices with bone grafts into the remaining cavity. Extensive research has been conducted on operative complications such as a failure of fusion or non-union of the vertebral bodies. Multiple factors including surgical, implant, and patient factors influencing the rate of complications have been identified. Patient factors include age, sex, osteoporosis, and patient anatomy. Complications can also be influenced by the interbody cage design. The geometry of the bony endplates as well as their corresponding material properties guides the design of interbody cages, which vary considerably across patients with spinal disorders. However, studies on the effects of such variations on the rate of complications are limited. Therefore, this study aimed to perform a systematic review of lumbar endplate geometry and material property factors in LIF failure.

Methods

Search keywords included ‘factor/cause for spinal fusion failure/cage subsidence/cage migration/non-union’, ‘lumbar’, and ‘interbody’ in electronic databases PubMed and Scopus with no limits on year of publication.

Results

In total, 1341 articles were reviewed, and 29 articles were deemed suitable for inclusion. Adverse events after LIF, such as cage subsidence, cage migration, and non-union, resulted in fusion failure; hence, risk factors for adverse events after LIF, notably those associated with lumbar endplate geometry and material properties, were also associated with fusion failure. Those risk factors were associated with shape, concavity, bone mineral density and stiffness of endplate, segmental disc angle, and intervertebral disc height.

Conclusions

This review demonstrated that decreased contact areas between the cage and endplate, thin and weak bony endplate as well as spinal diseases such as spondylolisthesis and osteoporosis are important causes of adverse events after LIF. These findings will facilitate the selection and design of LIF cages, including customised implants based on patient endplate properties.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03091-8.

Biomechanical Evaluation of Stand-Alone Oblique Lateral Lumbar Interbody Fusion Under 3 Different Bone Mineral Density Conditions: A Finite Element Analysis

OBJECTIVE

To evaluate the biomechanical stability of stand-alone (SA) oblique lateral interbody fusion (OLIF) under different bone mineral density conditions.

METHODS

The finite element model of L2-L5 was reconstructed and verified via computed tomography scan images (M0). The L4-L5 segment of SA OLIF was created based on the validation model. By changing bone mineral density, SA OLIF was established in the normal bone mineral density group (M1), osteopenia group (M2), and osteoporosis group (M3). A 500 N vertical axial preload was imposed on the superior surface of L2, and a 10 N-m moment was applied on the L2 superior surface along the radial direction to simulate 6 different physiological motions: flexion, extension, left and right lateral bending, left and right rotation.

RESULTS

Compared with M0, the range of motion of the fusion segment was significantly reduced, and the maximum stress of the upper and lower end plates was significantly increased in all motion modes. Compared with M1, the maximum relative increases of range of motion, cephalic end-plate stress and tail end-plate stress of M2 in the L4-L5 segment were 39.1%, 9.9%, and 10.7%, and the maximum increases of the above parameters in M3 were 100%, 28.9%, and 31.6%. The maximum stress of the tail end plate of the M3 model during flexion was 54.617 MPa, which was very close to the yield stress of the lamellar bone (60 MPa).

CONCLUSIONS

With the increase of the degree of osteoporosis, the maximum stress on the upper and lower end plates of the fusion segment increased significantly, thus increasing the potential risk of implant subsidence. SA OLIF could not provide sufficient stability for patients with osteoporosis.

Endplate injury as a risk factor for cage retropulsion following transforaminal lumbar interbody fusion: An analysis of 1052 cases

Although transforaminal lumbar interbody fusion (TLIF) is a widely accepted procedure, major complications such as cage retropulsion (CR) can cause poor clinical outcomes. Endplate injury (EI) was recently identified as a risk factor for CR, present in most levels developing CR. However, most EIs occurred in non-CR levels, and the features of EIs in CR levels remain unknown.The aim of this study was to identify risk factors for CR following TLIF; in particular, to investigate the relationship between EIs and CR, and to explore the features of EIs in CR.Between October 2010 and December 2016, 1052 patients with various degenerative lumbar spinal diseases underwent bilateral instrumented TLIF. Their medical records, radiological factors, and surgical factors were reviewed and factors affecting the incidence of CR were analyzed.Twenty-one patients developed CR. Nine had back pain or leg pain, of which six required revision surgery. A pear-shaped disc, posterior cage positioning and EI were significantly correlated with CR (P < .001, P = .001, and P < .001, respectively). Computed tomography (CT) scans revealed the characteristics of EIs in levels with and without CR. The majority of CR levels with EIs exhibited apparent compression damage in the posterior part of cranial endplate on the decompressed side (17/18), accompanied by caudal EIs isolated in the central portion. However, in the control group, the cranial EIs involving the posterior part was only found in four of the total 148 levels (P < .001). Most of the injuries were confined to the central portion of the cranial or caudal endplate or both endplates (35 in 148 levels, 23.6%). Additionally, beyond cage breaching into the cortical endplate on lateral radiographs, a characteristic appearance of coronal cage misalignment was found on AP radiographs in CR levels with EIs.A pear-shaped disc, posterior cage positioning and EI were identified as risk factors for CR. EI involving the posterior epiphyseal rim had influence on the development of CR. Targeted protection of the posterior margin of adjacent endplates, careful evaluation of intraoperative radiographs, and timely remedial measures may help to reduce the risks of CR.

Transforaminal Endoscopic Surgical Treatment for Posterior Migration of Polyetheretherketone Transforaminal Lumbar Interbody Fusion Cage: Case Series

OBJECTIVE

This study aims to report the clinical outcome of treating lumbar radiculopathy in the setting of retropulsed polyetheretherketone (PEEK) transforaminal lumbar interbody fusion (TLIF) cages with transforaminal endoscopic spine surgery.

METHODS

A retrospective study of 8 patients with lumbar radiculopathy in the setting of a retropulsed PEEK TLIF cage were included from January 2014 to January 2019. The inclusion criteria were 1) lumbar radiculopathy in the setting of a retropulsed PEEK TLIF cage causing nerve compression and 2) follow-up at least 1 year. Patients were asked to complete the following questionnaires for outcome evaluation: visual analog scales (VAS) for leg pain and the Oswestry Disability Index (ODI).

RESULTS

Eight patients underwent transforaminal endoscopic surgery for treatment of radiculopathy in the setting of a retropulsed PEEK TLIF cage in the 5-year period evaluated. One year after surgery, the VAS and ODI scores showed a significant decrease: average preoperative VAS and ODI scores were 6.9 ± 1.2 and 50.5 ± 10.9, and 1-year postoperative VAS and ODI scores were 2.3 ± 1.3 and 17.3 ± 5.1.

CONCLUSIONS

Transforaminal endoscopic spine surgery for the treatment of a retropulsed PEEK TLIF cage is a safe and effective approach with low morbidity and acceptable complication rates for patients with radiculopathy secondary to a retropulsed PEEK TLIF cage. Compared with a more invasive approach to removing or drilling the PEEK TLIF cage, endoscopic spine surgery could achieve a similar improvement in the patient-reported outcomes with possibly fewer complications.

Comparison of Different Approaches in Lumbosacral Spinal Fusion Surgery: A Systematic Review and Meta-Analysis

We aimed to systematically review the literature to analyze the differences in posterior lumbar interbody fusion (PLIF), anterior lumbar interbody fusion (ALIF), and transforaminal lumbar interbody fusion (TLIF), focusing on the complications, risk factors, and fusion rate of each approach. Spinal fusion surgery is a well-established surgical procedure for a variety of indications, and different approaches developed. The various approaches and their advantages, as well as approach-related pathology and complications, are well investigated in spinal surgery. Focusing only on lumbosacral fusion, the comparative studies of different approaches remain fewer in numbers. We systematically reviewed the literature on the complications associated with lumbosacral interbody fusion. Only the PLIF, ALIF, or TLIF approaches and studies published within the last decade (2007–2017) were included. The exclusion criteria in this study were oblique lumbar interbody fusion, extreme lateral interbody fusion, more than one procedure per patient, and reported patient numbers less than 10. The outcome variables were indications, fusion rates, operation time, perioperative complications, and clinical outcome by means of Visual Analog Scale, Oswestry Disability Index, and Japanese Orthopaedic Association score. Five prospective, 17 retrospective, and two comparative studies that investigated the lumbosacral region were included. Mean fusion rates were 91,4%. ALIF showed a higher operation time, while PLIF resulted in greater blood loss. In all approaches, significant improvements in the clinical outcome were achieved, with ALIF showing slightly better results. Regarding complications, the ALIF technique showed the highest complication rates. Lumbosacral fusion surgery is a treatment to provide good results either through an approach for various indications as causes of lower back pain. For each surgical approach, advantages can be depicted. However, perioperative complications and risk factors are numerous and vary with ALIF, PLIF, and TLIF procedures, as well as with fusion rates.

Risk Factors Affecting Cage Retropulsion into the Spinal Canal Following Posterior Lumbar Interbody Fusion: Association with Diffuse Idiopathic Skeletal Hyperostosis

Study Design

This was a retrospective observational study.

Purpose

We identify risk factors, including physical and surgical factors, and comorbidities affecting cage retropulsion following posterior lumbar interbody fusion (PLIF).

Overview of Literature

Diffuse idiopathic skeletal hyperostosis (DISH) is considered a risk factor for reoperation after PLIF. We evaluated the effect of DISH on cage retropulsion into the spinal canal, which may require surgical revision for severe neurological disorders.

Methods

A total of 400 patients (175 men, 225 women) who underwent PLIF were observed for >1 year. Factors investigated included the frequency of cage retropulsion and surgical revision. In addition, physical (age, sex, disease), surgical (fusion and PLIF levels, cage number, grade 2 osteotomy), and comorbid (DISH, existing vertebral fracture) factors were compared between patients with and without cage retropulsion. Factors related to surgical revision during the observation period were also considered.

Results

Cage retropulsion occurred in 15 patients and surgical revision was performed in 11. Revisions included the replacement of pedicle screws (PSs) with larger screws in all patients and supplementary implants in 10. Among the patients with cage retropulsion, the average PLIF level was 2.7, with DISH present in nine patients and existing vertebral fractures in six. Factors affecting cage retropulsion were diagnoses of osteoporotic vertebral fracture, multilevel fusion, single-cage insertion, grade 2 osteotomy, presence of DISH, and existing vertebral fracture. Multivariable analysis indicated that retropulsion of a fusion cage occurred significantly more frequently in patients with DISH and multilevel PLIF.

Conclusions

DISH and multilevel PLIF were significant risk factors affecting cage retropulsion. Revision surgery for cage retropulsion revealed PS loosening, suggesting that implant replacement was necessary to prevent repeat cage retropulsion after revision.

Assessment of the association between paraspinal muscle degeneration and quality of life in patients with degenerative lumbar scoliosis

The present study aimed to determine the characteristics of multifidus, erector spinae and psoas major degeneration in elderly patients with degenerative lumbar scoliosis (DLS) and the correlation between asymmetric changes and patient quality of life. A total of 49 patients with lumbar scoliosis (DLS group) and 38 healthy individuals (control group) were prospectively examined. The functional cross-sectional area, cross-sectional area difference index (CDI) and fat infiltration rate (FIR) of the multifidus, erector spinae and psoas major at the apical vertebral level were measured using MRI. The visual analogue scale (VAS) score, Oswestry Disability Index (ODI) and 36-item Short Form Health Survey (SF-36) score were used to evaluate patient quality of life. Correlations between the degree of asymmetric muscular degeneration and quality of life were analysed. The CDI of the multifidus, erector spinal and psoas major was higher in the DLS group compared with that in the control group. The CDI of the multifidus was found to be positively associated with the Cobb angle of lumbar scoliosis. Similar results were obtained for fat infiltration between the two groups. In addition, the CDI and FIR difference index of the multifidus was positively correlated with the VAS score and ODI but negatively correlated with the SF-36 score. The quality of life significantly decreased with increasing asymmetric atrophy and fat infiltration in the multifidus. Thus, strategies to enhance the function of the multifidus may have a positive impact on quality of life (Chinese Clinical Trial Registry, registration date, 2018.11.12; registration no. ChiCTR1800019459.).

Standalone oblique lateral interbody fusion vs. combined with percutaneous pedicle screw in spondylolisthesis

Background

To compare standalone oblique lateral interbody fusion (OLIF) vs. OLIF combined with posterior bilateral percutaneous pedicle screw fixation (OLIF combined) for the treatment of lumbar spondylolisthesis.

Methods

This was a retrospective study of patients who underwent standalone OLIF or combined OLIF between 07/2014 and 08/2017 at two hospitals in China. Direct decompressions were not performed. Visual analog scale (VAS), Oswestry Disability Index (ODI), satisfaction rate, anterior/posterior disc heights (DH), foraminal height (FH), foraminal width (FW), cage subsidence, cage retropulsion, fusion rate, and complications were analyzed. All imaging examinations were read independently by two physicians and the mean measurements were used for analysis.

Results

A total of 73 patients were included: 32 with standalone OLIF and 41 with combined OLIF. The total complication rate was 25.0% with standalone OLIF and 26.8% with combined OLIF. There were no differences in VAS and ODI scores by 2 years of follow-up, but the scores were better with standalone OLIF at 1 week and 3 months (P < 0.05). PDH and FW was smaller in the combined OLIF group compared with the standalone OLIF group before and after surgery (all P < 0.05). There were significant differences in FH before surgery and at 1 week and 3 months between the two groups (all P < 0.05), but the difference disappeared by 2 years (P = 0.111). Cage subsidence occurred in 7.3% (3/41) and 7.3% (3/41) of the patients at 3 and 24 months, respectively, in the combined OLIF group, compared with 6.3% (2/32) and 15.6% (5/32), respectively, in the standalone OLIF group at the same time points (P = 0.287). There was no cage retropulsion in both groups at 2 years. The fusion rate was 85.4%(35/41) in the combined OLIF group and 84.4% (27/32) in the standalone OLIF group at 3 months(P = 0.669). At 24 months, the fusion rate was 100.0% in the combined OLIF group and 93.8% (30/32) in the standalone OLIF group (P = 0.066).

Conclusion

Standalone OLIF may achieve equivalent clinical and radiological outcomes than OLIF combined with fixation for spondylolisthesis. The rate of complications was similar between the two groups. Patients who are osteoporotic might be better undergoing combined rather than standalone OLIF. The possibilty of proof lies within a future prospective study, preferably an RCT.

Cage positioning as a risk factor for posterior cage migration following transforaminal lumbar interbody fusion - an analysis of 953 cases

Background

The risk of posterior cage migration (PCM) exists when a fusion cage is used for transforaminal lumbar interbody fusion (TLIF). This complication is influenced by contact pressure between the endplate and the cage. Previous reports demonstrated that anteriorly located cages bore more load and had greater strain than posteriorly located cages. However, there have been no detailed reports on the correlation between cage positioning and PCM.

Methods

From March 2014 to October 2015, we reviewed 953 patients receiving open transforaminal lumbar interbody fusion (TLIF) and bilateral pedicle screw instrumentation. One hundred patients without PCM were randomly sampled as the control group. Postoperative sagittal and coronal cage positions in the disc space were evaluated with the ‘depth ratio’ and the ‘coronal ratio’. The demographic data of patients with and without PCM were compared to detect patient-related factors. Radiographic and cage related parameters, including cage position, preoperative disc height, preoperative spine stability, cage geometry, cage size, and height variance (= cage height – preoperative disc height) were compared between the PCM group and the control group. Univariate analyses and a multivariate logistic model were used to identify risk factors of PCM.

Results

Posterior cage migration occurred in 24 (2.52%) of 953 patients. The univariate and multivariate analyses revealed that those with a decreased depth ratio (OR, 9.78E-4; 95% CI, 9.69E-4 – 9.87E-4; p < 0.001) and height variance (OR, 0.757, 95% CI, 0.575–0997, p = 0.048) had a significantly higher risk of developing PCM.

Conclusions

Our results verified that posteriorly located cages and undersized cages are more prone to developing PCM, which may aid surgeons in making optimal decisions during TLIF procedures.

[Safety and efficacy of an electron beam melting technique-manufactured titanium mesh cage for lumbar interbody fusion]

BACKGROUND

Electron beam melting (EBM) technique enables cage design changes such as the integration of guide rails on the cage surface or a 3D matrix for osseointegration. A change in manufacturing technique or design can lead to a decreased fusion rate or impaired applicability.

OBJECTIVE

The aim of the present study was to evaluate cage handling, lordosis reconstruction capability, and fusion rate 1 year after surgery.

MATERIALS AND METHODS

In this study, 50 patients who had undergone minimally invasive transforaminal lumbar interbody fusion (TLIF) or open posterior lumbar interbody fusion (PLIF) using an EBM-manufactured cage were retrospectively included. Fusion evaluation was based on routinely performed CTs and flexion-extension radiographs 12 months postoperatively. Lumbar and segmental lordosis were compared between pre-, post, and 1‑year follow-up. Postoperative cage position was used for evaluation of cage handling.

RESULTS

The radiological fusion rate was 97% at the 1‑year follow-up. Two cages were placed into the endplates during surgery without an effect on fusion. In 31% of the cages, placement at the anterior third of the disk space was possible. Lumbar lordosis was improved by a mean of 5° and segmental lordosis by a mean of 4°. At final follow-up, 1° was lost in both parameters. No implant-associated complications were registered.

CONCLUSION

The implant is safe and leads to a very high fusion rate. A learning curve results from the fact that the cage follows a defined radius dictated by the guide rails. Addressing this, exact placement at the anterior endplate can be achieved.